Scrobic (Paspalum scrobiculatum L.) is a vigorous, tufted (up to 60 cm diameter) and slender perennial grass. It grows to a height of 0.3-1 m. The roots are rather shallow and the stems are ascending, branched and somewhat succulent. Leaf blades are 15-40 cm long, 5-12 mm wide, pale green. Leaf sheaths and leaves are glabrous. The inflorescence is a panicle, generally consisting of 3-4 racemes, 4-9 cm long. The spikelets are arranged in two or three rows. Seeds are ellipsoidal, 2 mm long, 1.5 mm wide and light brown coloured (Ecoport, 2010; Galinato et al., 1999).

There are two forms of scrobic:

Kodo millet(Paspalum scrobiculatum var. scrobiculatum) is cultivated as an annual. It has been cultivated for 3000 years in India where it is considered as a minor cereal crop except in the Deccan where it is a cereal of utmost importance. It is grown as a single crop or as the major cereal in mixed cultures. The seeds are used as human food: grains are ground into meal and used for puddings (Quattrocchi, 2006). In Africa, it is harvested as a wild cereal (FAO/ICRISAT, 1996) and is mainly considered as a famine food (NRC, 1996). Kodo millet varies considerably: light red grains are said to be sweet tasting and dark gray ones to be bitter (Galinato et al., 1999). Yields range from 450 to 900 kilograms of grain per hectare (Stephen et al., 1986). Kodo millet is well suited to dry conditions (Galinato et al., 1999).

Scrobic originated from Africa and is now widespread in the Old World tropics. It was first introduced to India and is now cultivated in other parts of Asia. Scrobic is common in upland rice in India, Indonesia, the Philippines, Thailand and Vietnam, and is also present in Bangladesh and Myanmar (Galinato et al., 1999). Scrobic was introduced to Australia from Zimbabwe in 1931 (FAO, 2010).

Scrobic is commonly found on disturbed sites or as a weed in cropping land (Galinato et al., 1999). It is found from sea level up to an altitude of 1500 m. It has no particular climatic preference provided that the average day temperatures are comprised between 25 and 27°C and that no frost occurs. The soil should remain wet (annual rainfall ranging from 800 to 1600 mm). It is well adapted to waterlogged or flooded soils. Scrobic thrives in cultivated fields, pastures, in marshes and along roadsides, dikes, bunds and canals. Wild scrobic has only limited drought tolerance as it has relatively shallow roots. Kodo millet thrives in drier conditions (Ecoport, 2010; FAO, 2010; Galinato et al., 1999).

Scrobic prefers very fertile and very clayey soils. It responds to well fertilized soils (Galinato et al., 1999; Baki et al., 1992), but tolerates poor soil fertility if there is little competition with other species. Scrobic prefers full sunlight but it is also found in young rubber and oil palm plantations or black pepper farms because it can tolerate and flourish with only 30-50% sunlight (Baki et al., 1992).

Soil erosion control

Scrobic may have some value as a cover crop in its ecological niche (FAO, 2010).

Nutritional aspects

Potential constraints

Paspalum ergot

During their development, scrobic seeds can be attacked by the paspalum ergot (Claviceps paspali) whose sclerotia grow instead of the grains. These sclerotia contain an alkaloid that may be fatal to both humans and animals. Other fungi (Sorosporium paspali and Uredo paspali-scrobiculati) are almost invariably present in the outer husks of the grain, and may also be responsible for scrobic toxicity (Baki et al., 1992). Symptoms of ergotism in affected animals are associated with central nervous derangement and appear in the following order: excitement, distrust of people and a tendency to attack. Later, animals may tremble, appear to lack muscular control, stagger and fall. Affected animals may recover in a few days if removed from infected areas in the early stages of excitement (Cook et al., 2005; FAO, 2010; McMullen et al., 1998).

In order to prevent poisoning, the seeds of kodo millet are carefully removed from the outer husks and are winnowed to scatter the spores, so that only clean and healthy grains are used as food (Galinato et al., 1999).

Mycotoxins

Oxalic acid

Scrobic forage contains 0.23% DM of total oxalic acid but this does not cause toxicity (FAO, 2010).

Ruminants

Wild scrobic forage is palatable at all stages and is readily eaten by cattle and buffaloes (Quattrocchi, 2006; Galinato et al., 1999). In Ghana, it was reported to be one of the most heavily grazed herbage species for cattle, sheep and goats (Tetteh, 1974).

Composition and digestibility

In Australia, the nutritive value of wild scrobic was found to be highly variable throughout the year. It was readily eaten and highly digestible up to flowering (70-75% DM digestibility and 50-70% crude protein digestibility). After frosting, intake and digestibility decreased substantially: DM digestibility was down to 30% and crude protein digestibility became negative (Milford, 1960). In Bangladesh, an intermediate OM digestibility of 54% was recorded (Zaharaby et al., 2001). Protein content was very low in Australia (2.8 to 7.3% DM) (Milford, 1960), but higher (11.7% DM) in Bangladesh (Zaharaby et al., 2001).

Pasture

Beef cattle

Scrobic pastures have been particularly studied in the context of beef cattle production in Australia, where it is able to support production during summer (December to March). Due to its high frost susceptibility, scrobic is unsuitable for continuously grazed pastures in areas where severe frosts are recorded, but it can be valuable in frost-free areas and can be a very useful subtropical pasture grass (Milford, 1960). For beef cattle, scrobic has a nutritive value similar to that of pangola grass (Digitaria eriantha) but more variable. At a stocking rate of 1.67 head/ha, scrobic pasture resulted in a live-weight gain of 240 kg/ha/year in young beef cattle, slightly lower than with pangola and much lower than with Paspalum dilatatum (315 kg/ha/year). At a higher stocking rate (2.5 head/ha), scrobic supported higher performances than pangola grass, Paspalum dilatatum and Paspalum plicatulum (345 vs. 305, 246 and 223 kg/ha/year respectively) (Bryan, 1968). When grazed as a component of a sown complex pasture mixture, light stocking rates (about 1.7 head/ha) were preferable (Bryan et al., 1973).